Calibration stop for fuel injectors and the like



$4M O E W N, W R 4mN w D T M G 7 mm G Oct. 10, 1967 G. D. NUSBAUM CALIBRATION STOP FOR FUEL INJECTORS AND THE LIKE Filed June 24, 1965 United States Patent 3,346,188 CALIBRATION STOP FOR FUEL INJECTORS AND THE LIKE George D. Nusbaum, Diesel Service Co., 2509 E. Lake St., Minneapolis, Minn. 55406 Filed June 24, 1965, Ser. No. 466,683 5 Claims. (Cl. 239-90) This invention relates generally to improvements in fuel injector devices for internal combustion engines, and more particularly, to means for calibrating the metering of liquid petroleum fuel introduced through the combustion chamber of an engine by a fuel injector.

It is known to those familiar with multi-cylinder internal combustion engines using fuel injectors, such as diesel engines, that the quantity of fuel introduced to each cylinder for each combustion cycle thereof be the same as that introduced to every other cylinder. Extreme uniformity of fuel injection for all cylinders at all engine speeds is essential, not only to the achievement of high engine performance, but also to the prevention of damage to the engine from unbalanced operation of the several cylinders. Hence, it is very important that the injector fuel output be calibrated with a high degree of accuracy, and that no attempts be made to disturb or change the settings of any of the injectors during operation of the engine.

In many fuel injectors of present manufacture, the liquid fuel is injected to the combustion chamber of the engine by means of reciprocatory plunger in the injector, the plunger and associated parts of the injector having cooperating fuel passages, the quantity of fuel being regulated by rotation of the plunger. Rotation is imparted to the plunger by means of a gear rack slidably mounted in the injector body and a cooperating pinion mounted on the plunger for common rotation therewith and for axial sliding movements relative thereto. The gear racks of all of the fuel injectors of an engine are interconnected for common movement by well-known linkage controlled by the operator for varying engine speed.

Heretofore, in calibrating injectors of the above type, a calibrating gauge has been used, such a gauge being used in connection with the setting of a given portion of the gear rack, such as one end thereof, relative to a slide member slidably mounted on the body of the injector for movements longitudinally of the rack and releasably locked in desired position by a clamping screw or the like. With such an arrangement, the injector is mounted in a conventional calibrating stand and regulated to produce a given fuel output per stroke of the plunger. With the help of the gauge, the slide member is moved to the proper position relative to the end of the gear rack and locked in place by the clamping screw. A similar gauge is used when the injector is positioned on the engine, for adjusting the regulating linkage, so that all of the injectors on a given engine have identical fuel output at any given en: gine speed.

While the above-described calibration slide member has worked very well in practice, it has the disadvantage of being accessible to general mechanics not sufficiently well acquainted with fuel injector problems to know that, once adjusted and set, the slide members should not be moved at any time during use of the injector in an engine. In many stances, in attempts to locate minor troubles in engine operation, these slides have been moved and the linkage readjusted relative thereto, usually resulting in impaired operation. Hence, an important object of this "ice invention is the provision of calibration means for fuel injectors which is substantially tamper-proof.

Another object of this invention is the provision of a calibration gauging member which can be easily adjusted with a high degree of accuracy.

Another object of this invention is the provision of a calibration member which, when adjusted as desired, can be positively locked in its adjusted position against accidental movement.

Another object of this invention is the provision of a calibration or gauging member which can be easily applied to a fuel injector body with a minimum of modification to the body and with a minimum of machining.

Still another object of this invention is the provision of a calibrating or gauging member which can be easily removed and replaced when the fuel injector is being repaired or rebuilt.

To the above ends, I provide a calibration or gauging member in the form of a commercially available machine screw or bolt having an adjustment tool engaging portion at one end and screw threaded into :a fuel injector body in spaced parallel relation to the regulator gear rack for adjustment movement parallel to the direction of reciprocatory movement of the rack. I further provide spacer means for selective insertion between a portion of the screw or bolt and an underlying portion of the body to limit movement of the bolt in one direction. A tool barrier element in the nature of a plug or the like is applied to the tool-engaging portion of the screw or bolt to disguise the same against recognition as such, the barrier element being easily removable by persons having knowledge of the nature thereof.

The above, and still further highly important objects and advantages of this invention will become apparent from the following detailed specification, appended claims and attached drawings.

Referring to the drawings, which illustrate the invention, and in which like reference characters indicate like parts throughout the several views:

FIG. 1 is a view in side elevation of a fuel injector, some parts being broken away and some parts being shown in section;

FIG. 2 is a fragmentary view in side elevation as seen from the line 2-2 of FIG. 1;

FIG. 3 is a transverse section taken substantially on the line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary section taken on the irregular line 44 of FIG. 2; and

FIG. 5 is a view corresponding generally to FIG. 4 but showing a tamper-proofing plug applied to the calibration stop or gauging member of this invention.

Referring with greater detail to the drawings, a fuel injector is shown as comprising a body member 1 having secured thereto a hollow tapered barrel 2, which projects longitudinally outwardly from one side of the body 1. At its opposite side, the body 1 is formed to provide a tubular guide 3 for reception of a tappet 4 having a diametrically enlarged head or flange 5 at its outer end. A coil compression spring 6 is interposed between the head or flange 5 and the adjacent side of the body member 1 and yieldingly urges the tappet 4 in one direction of axial reciprocatory movement thereof. The tubular guide 3 is formed to provide an axial slot 7 for reception of a guide pin or the like 8 that projects radially outwardly from the tappet 4 to hold the tappet 4 against rotation on its axis within the tubular guide 3 and body 1. Adjacent the inner end of the spring 6, the body member 1 is provided with inlet and outlet fittings 9 and 10 respectively, whereby the injector is interposed in a fuel line, not shown. At its opposite side, adjacent the inner end of the barrel 2, the body member 1 is provided with a locating pin or the like 11 for positioning the injector on an internal combustion engine, not shown.

The tapered barrel 2 is adapted to be closely fitted in a suitable opening in a wall of an internal combustion engine, not shown, and has an outer end 12 adapted to project into the combustion chamber of the engine. A nozzle element 13 is mounted in the outer end portion 12 of the barrel 2 and is provided with a longitudinally extending fuel passage 14 which defines one or more outlet openings 15 outwardly of the adjacent end 12 of the barrel 2, and a tapered valve seat 16 disposed longitudinally inwardly of the outlet openings 15. The fuel passage 14 inwardly of the valve seat 16 is radially displaced from the axis of the nozzle 13, an elongated needle valve element 17 being axially disposed in the nozzle 13 for longitudinal sliding movements therein. At its outer end, the needle valve 17 is tapered, as at 18, to make seating engagement with the valve seat portion 16. The inner end of the needle valve element 17 is adapted to engage a tubular stop member 19 mounted in the barrel 2, to limit axial movement of the needle valve element 17 away from seating engagement with the seat 16. The valve element 17 is formed to provide a diametrically reduced stem portion 20 that extends axially from the inner end of the needle valve element into the tubular stop member 19, a flanged cap 21 being mounted on the projected end of the stem portion 20. A pair of cooperating axially aligned retainer members 22 and 23 overlie the inner end of the tubular stop member 19, the tubular member 22 providing stop means for the inner end of a coil compression spring 24 the outer end of which seats against the flanged cap 21 to yieldingly urge the needle valve element 17 into seating engagement with the valve seat 16 of the nozzle 13. The retainer member 23 is formed to provide an axial fuel passage 25 that communicates with a cavity 26 defined by the retainer members 22 and 23 and in which is mounted a conventional check valve 27. The retainer member 22 is formed to provide a fuel passage 28 that communicates with the cavity 26 below the check valve 27 and one end of a longitudinally extending fuel passage 29 the other end of which communicates with the fuel passage 14 and the nozzle 13.

Mounted in the barrel 2 between the retainer member 23 and the body 1 is an elongated bushing 30 having an axial bore 31 that communicates at its lower end with the fuel passage 25 in the retainer member 23. The bushing 30 is of sulficiently smaller diameter than the internal diameter of the hollow barrel 2 to form therewith an annular gallery 32 extending substantially the length of the bushing 30 and communicating with the inlet and outlet fittings 9 and 10 through means including passages 33 and 34 in the body 1. A pair of axially spaced upper and lower spill ports 35 and 36 respectively extend axially through the bushing 30 to establish fluid communication between the bore 31 and an nular gallery 32. An elongated cylindrical plunger 37 is closely fitted within the bore 31 for rotary and axial sliding movement relative to the bushing 30, and at its upper end is operatively connected to the tappet 4 for common axial reciprocatory movement therewith. The plunger 37 is so positioned within the bushing 30 that the lower end 38 of the plunger 37 moves between a plunger retracted position slightly above the lower spill port 36 to a plunger depressed position slightly above the lower end of the bushing 30 and the retainer member 23. Above its lower end 38, the plunger 37 is formed to provide a circumferential channel 39 having generally helical upper and lower sides or edges 40 and 41 respectively, the latter being disposed below the upper spill port 35 and the former passing over the spill port 35 during reciprocatory movement of the plunger 37. Between the upper and lower channel edges 40 and 41, the plunger 37 is provided with a transverse passage 42 that communicates with an axial passage 43 extending downwardly from the transverse passage 42 through the lower end 38 of the plunger 37.

In FIG. 1, with the plunger 37 in its retracted position, the needle valve element 17 is shown in its open position only in the interest of clarity. Normally, with the plunger 37 in its retracted position shown, the needle valve element 17 would be disposed in its valve-closed position with the tapered portion 18 thereof seated on the tapered seat 16. Assuming that the various fluid passages 14, 28, 29, 33 and 34, as well as the annular gallery 32, spill ports 35 and 36, and bore 31 below the plunger 37, are filled with liquid fuel, downward movement of the plunger 37 will close the spill port 36, after which a liquid fuel in the bore 31 will flow upwardly and outwardly through the passages 43 and 42 to the spill port 35 until the channel edge 40 closes the spill port 35. During further downward movement of the plunger 37, liquid fuel in the bore 31 will be subject to extreme pressure by the plunger 37 to cause opening of the needle valve element 17 against bias of the spring 24, and the fuel will be sprayed into the combustion chamber through the outlet openings 15 until the channel edge or side 41 moves into register with the spill port 36. The liquid fuel in the bottom portion of the bore 31 can then escape through the passages 43 and 42 in the plunger 37 reducing pressure in the nozzle 13 and permitting the spring 24 to move the needle valve element 17 to its closed position. During retracting or upward movement of the plunger 37, the check valve 27 is closed, whereby to maintain the cavity 26 and passages 14, 28 and 29 filled with liquid fuel. The extent of reciprocatory movement of the plunger 37 is the same for all engine speeds. The channel edges 40 and 41 each being generally in the nature of a helix, the amount of fuel discharged to the combustion chamber is varied by rotation the plunger 37 on its own axis. This is accomplished by a pinion 44 mounted on the upper end portion of the plunger 37 for common rotation therewith and for axial sliding movements relative thereto, and a cooperating gear rack 45 extending through a transverse opening 46 in the body member 1 and having intermeshing engagement with the pinion 44. The gear rack 45 is suitably keyed, as indicated at 47, to be maintained in proper intermeshing relationship with the pinion 44, see particularly FIG.

3. One end of the gear rack 45 projects outwardly from the body member 1 and is provided with suitable means, such as a ball 48 for connection to conventional control linkage, not shown.

The above described fuel injector is one of several commonly used with internal combustion engines of the fuel injection type, and has been described in detail so that a full understanding of the operation thereof may be had. From the above, it will be noted that movement of the gear rack 45 in one direction decreases the amount of fuel injected to the combustion chamber, while movement of the rack 45 in the opposite direction increases the quantity of fuel injected to the combustion chamber.

As above indicated, in multi-cylinder engines using fuel injectors, it is highly important that, at any given engine speed, each fuel injector delivers a quantity of fuel to its respective combustion chamber equal to that delivered by every other injector. Hence, each injector is calibrated prior to installation in an engine, calibration thereof generally using a reference point on the body member 1 and another reference point on the rack 45. Heretofore, in practice, the reference point on the body 1 would be the side surface 49 thereof, the cooperating reference point on the rack 45 being the outer end surface 50 thereof. With the use of a proper gauge to set the end surface 50 of the rack 45 a predetermined distance from the surface 49 of the body 1, and operating the injector in a calibration stand, the quantity of fuel injected by the injector can be quickly and easily determined. However, due to variations in machining and because of the close tolerances required, a given distance between the surfaces 49 and 50 in one injector does not always result in an equal fuel output of other injectors having the same gauged distances between the surfaces 49 and 50. Hence, it has been heretofore necessary to provide injectors in matched sets, so that servicing or repair of any one thereof becomes a problem when recalibrating. In such instances, spare injectors having equal output characteristics must be kept on hand. It should be borne in mind that, when fuel injectors are installed in an engine, an installing gauge identical to the calibrating gauge is used, and the control linkage is adjusted to each rack 45 as required by the calibrated setting thereof.

For the purpose of more accurately calibrating fuel injectors, and for the purpose of rendering the fittings thereof substantially tamper-proof, I provide a gauging member or calibrating stop comprising a machine screw or bolt 51 having a head 52 at one end thereof. The head 52 is formed to provide an axially outwardly opening recess 53 which, for the purpose of the present example, is cross-sectionally polygonal to receive the bit of a driving tool. The body 1 is drilled and tapped to receive the screw 51, and counterbored, as indicated at 54, whereby to receive at least a portion of the head 52 and provide an annular shoulder 55. One or more washers 56 of accurately machine predetermined thickness are interposed between the shoulder 55 and the base portion of the head 52.

In calibrating a fuel injector using the adjustable gauging member or screw 51, a calibrating gauge, such as shown by dotted lines in FIG. 4 and indicated by the reference numeral 57 is used. The injector is mounted in a calibrating stand, and the rack 45 thereof adjusted to a predetermined fuel output. The gauging member 51 is then adjusted so that the outer end thereof is disposed the proper distance from the end surface 50 of the rack 45, this distance being measured by the gauge 57. The dimension from the outer end of the gauging member 51 and the adjacent surface 49 of the body is then measured, the gauging member 51 unscrewed from the body 1, and a suflicient number of washers 56 are mounted on the gauging member or screw 51 to cause the outer end of the head 52 to project outwardly from the surface 49 to the measured dimension when the screw 51 is again threaded into the body 1 until the base of the head 52 bottoms tightly against the washers 56 interposed therebetween and the shoulder 55. When the injectors are installed in an engine, another gauge having identical gauging dimensions as the gauge 57 is used, and the control linkage of the engine is adjusted to the rack 45 when positioned with the use of the installing gauge.

An important feature of the above-described arrangement is a filler plug 58 for the recess 53. The filler plug 58 is preferably of relatively inert metal having a low melting point such as lead or the like. When a gauging member or screw has been properly adjusted and set as above-described, the plug 58 is poured into the recess 53 in a molten state until the recess is completely filled to the level of the outer end of the head 52. Thus, when the injector is placed or installed in an engine, no further adjustment can be made of the gauging member or screw 51 without first removing the plug 58 by chiseling or melting the same from the recess 53. In fact, the line of joinder between the plug 58 and head 52 is unnoticeable to the casual observer such as a general mechanic who will not be tempted to adjust the gauging member once the same has been set at the factory or place of service or repair.

The gauging member 51, as shown, is in the nature of an Allen head screw having a cross-sectionally hexagonal recess 53 therein. However, it will be appreciated that any type of screw head may be used having a recess that may be plugged. The washers 56 are preferably of various predetermined thicknesses and are selectively usable in various combinations to obtain the gauge dimension between the outer end of the screw 51 and the outer end of the rack 45 when the gauging member or screw 51 is tightly screw threaded into the body member 1.

My invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the objectives set forth; and, while I have shown and described a commercial form of calibrating stop or member, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention, as defined in the claims.

What is claimed is:

1. A fuel injector for internal combustion engines including body means having a fuel feeding and metering device therein and a reciprocatory member operatively coupled to said device for regulating the quantity of fuel discharged from the injector by said feeding and metering device, characterized by calibrating means for said reciprocatory member, said calibrating means comprising, a gauging member mounted in said body for movements in opposite directions parallel to the direction of reciprocatory movement of said reciprocatory member and having an outer end portion projecting slightly outwardly of an adjacent surface portion of said body, stop means between said body and a portion of said gauging member positively limiting movement of the gauging member in one direction, said outer end of the gauging member having an adjustment tool-receiving portion, and a removable tool barrier element on said tool-receiving portion.

2. A fuel injector for internal combustion engines including body means having a fuel feeding and metering device therein and a reciprocatory member operatively coupled to said device for regulating the quantity of fuel discharged from the injector by said feeding and metering device, characterized by calibrating means for said reciprocatory member, said calibrating means comprising, a gauging member mounted in said body for movements in opposite directions parallel to the direction of reciprocatory movement of said reciprocatory member and having an outer end portion projecting slightly outwardly of an adjacent surface portion of said body, stop means between said body and a portion of said gauging member positively limiting movement of the gauging member in one direction, said outer end of the gauging member having a recess for reception of an adjusting tool, and a plug filling said recess and normally preventing insertion of an adjusting tool into said recess.

3. A fuel injector for internal combustion engines including body means having a fuel feeding and metering device therein and a reciprocatory member operatively coupled to said device for regulating the quantity of fuel discharged from the injector by said feeding and metering device, characterized by calibrating means for said reciprocatory member, said calibrating means comprising, a gauging member adjustably movably mounted in said body in opposite directions parallel to the direction of reciprocatory movement of said reciprocatory member and having an enlarged head partially recessed in said body, adjustable stop means underlying said enlarged head, said head having an axially outwardly opening recess for reception of an adjusting tool, and a plug filling said recess and normally preventing insertion of an adjusting tool into said recess.

4. A fuel injector for internal combustion engines including body means having a fuel feeding and metering device therein and a reciprocatory member operatively coupled to said device for regulating the quantity of fuel discharged from the injector by said feeding and mete-ring device, characterized by calibrating means for said reciprocatory member, said calibrating means comprising, a gang- 7 r r 8 ing bolt screw threadedly received in said body on an axis 5. The structure defined in claim 4 in which saidbody parallel to the direction of reciprocatory movement of said is countenbored to receive at least a portion of saidbolt reciprocatory member and having an enlarged head, stop vhead- 1 washer means on said bolt and engaging a portion of said Refemnce5 Cited body underlying said head'to limit movement of said bolt 5 UNITED STATES PATENTS in one direction, said bolt head having a recess for recep- 2,559,364 7/1951 Mashinter 239 9O tion of an adjusting tool, and a plug filling said recess'and 3,179,053 4/1965 Jordan normally preventing insertion of an adjusting tool into said V V recess. 7 V EVERETT W. KIRBY, Primary Exainmer. 

1. A FUEL INJECTOR FOR INTERNAL COMBUSTION ENGINES INCLUDING BODY MEANS HAVING A FUEL FEEDING AND METERING DEVICE THEREIN AND A RECIPROCATORY MEMBER OPERATIVELY COUPLED TO SAID DEVICE FOR REGULATING THE QUANTITY OF FUEL DISCHARGED FROM THE INJECTOR OF SAID FEEDING AND METERING DEVICE, CHARACTERIZED BY CALIBRATING MEANS FOR SAID RECIPROCATORY MEMBER, SAID CALIBRATING MEANS COMPRISING, A GAUGING MEMBER MOUNTED IN SAID BODY FOR MOVEMENTS IN OPPOSITE DIRECTIONS PARALLEL TO THE DIRECTION OF RECIPROCATORY MOVEMENT OF SAID RECIPROCATORY MEMBER AND HAVING AN OUTER END PORTION PROJECTING SLIGHTLY OUTWARDLY OF AN ADJACENT SURFACE PORTION OF SAID BODY, STOP MEANS BETWEEN SAID BODY AND A PORTION OF SAID GAUGING MEMBER POSITIVELY LIMITING MOVEMENT OF THE GAUGING MEMBER IN ONE DIRECTION, SAID OUTER END OF THE GAUGING MEMBER HAVING AN ADJUSTMENT TOOL-RECEIVING PORTION, AND A REMOVABLE TOOL BARRIER ELEMENT ON SAID TOOL-RECEIVING PORTION. 